Composite material having an aluminosilicate matrix, in particular made from barium aluminosilicate (bas) reinforced with metal oxide reinforcements, and method for preparing same

Abstract

A composite material consisting of a matrix made of at least one aluminosilicate notably selected from barium aluminosilicate BAS, barium and strontium aluminosilicate BSAS, strontium aluminosilicate SAS, and mixtures thereof, reinforced by reinforcements made of at least one metal or metalloid oxide, the expansion coefficient of which is close to that of said at least one aluminosilicate. A method for preparing said composite material. A composite material according to the invention notably finding its application in the aeronautical or aerospace field, for example for the manufacture of radomes.

1 - 21 . (canceled) 
     
     
         22 . A composite material comprising:
 a matrix made of at least one aluminosilicate, reinforced by reinforcements made of at least one metal or metalloid oxide,   wherein an expansion coefficient of said at least one metal or metalloid oxide is substantially similar to an expansion coefficient of said at least one aluminosilicate, and   wherein the at least one aluminosilicate is selected from barium aluminosilicate (BAS), barium and strontium aluminosilicate (BSAS), strontium aluminosilicate (SAS), and mixtures thereof.   
     
     
         23 . The composite material according to  claim 22 , wherein the matrix is made of barium aluminosilicate (BAS). 
     
     
         24 . The composite material according to  claim 23 , wherein the BAS in majority by mass comprises BAS of hexagonal structure. 
     
     
         25 . The composite material according to  claim 24 , wherein the reinforcements are made of alumina. 
     
     
         26 . The composite material according to  claim 23 , wherein the BAS in majority by mass comprises BAS of monoclinic structure. 
     
     
         27 . The composite material according to  claim 22 , wherein the reinforcements are made of silica and/or mullite. 
     
     
         28 . The composite material according to  claim 22 ,
 wherein the reinforcements made of at least one metal or metalloid oxide appear in one or several forms selected from particles and fabrics of fibers.   
     
     
         29 . The composite material according to  claim 22 , wherein the matrix represents 99 to 50% by mass of the material, and the reinforcements represent 1 to 50% by mass of the material. 
     
     
         30 . The material according to  claim 22 , wherein said material is a dense material with a density from 80% to 100% of a theoretical density. 
     
     
         31 . A method for preparing the composite material according to  claim 22 , wherein the following successive steps are carried out:
 a) placing a powder of at least one aluminosilicate selected from barium aluminosilicate (BAS), barium and strontium aluminosilicate (BSAS), strontium aluminosilicate (SAS), and mixtures thereof, into contact with reinforcements made of at least one metal or metalloid oxide, wherein an expansion coefficient of said at least one metal or metalloid oxide is substantially similar to an expansion coefficient of said at least one aluminosilicate;   b) sintering of said powder of at least one aluminosilicate and of the reinforcements made of at least one metal or metalloid oxide carried out by a hot sintering method with a pulsed electric field;   c) cooling the sintered powder and reinforcements; and   d) recovering the composite material.   
     
     
         32 . The method according to  claim 31 , wherein powder of at least one aluminosilicate is barium aluminosilicate (BAS) powder. 
     
     
         33 . The method according to  claim 32 , wherein the BAS in majority by mass comprises BAS of hexagonal structure. 
     
     
         34 . The method according to  claim 33 , wherein the BAS powder, which in majority by mass comprises BAS of hexagonal structure, is prepared by carrying out the following successive steps:
 mixing BaCO 3  powder and SiO 2  powder in a molar ratio of 1 BaCO 3  for 2SiO 2 ;   drying and then sintering the mixture of the BaCO 3  powder and of the SiO 2  powder to obtain a compound in majority consisting of the compound BaSi 2 O 5 ;   milling the compound in majority consisting of BaSi 2 O 5  to obtain a powder of said compound in majority consisting of BaSi 2 O 5 ;   mixing the powder of the compound in majority consisting of BaSi 2 O 5 , and the Al 2 O 3  powder, in a molar ratio of 1 BaSi 2 O 5  for 1 Al 2 O 3 ;   drying and then sintering the mixture of the powder of the compound in majority consisting of BaSi 2 O 5 , and of the Al 2 O 3  powder; and   milling the sintered mixture to obtain a BAS powder which in majority by mass comprises BAS of hexagonal structure.   
     
     
         35 . The method according to  claim 33 , wherein the reinforcements are made of alumina. 
     
     
         36 . The method according to  claim 31 , wherein tire BAS in majority by mass comprises BAS of monoclinic structure. 
     
     
         37 . The method according to  claim 36 , wherein the reinforcements are made of silica and/or mullite. 
     
     
         38 . The method according to any one of  claim 31 , wherein the reinforcements made of at least one metal or metalloid oxide appear in one or several forms selected from particles and fabrics of fibers. 
     
     
         39 . The method according to  claim 31 , further comprising:
 during step a), preparing a mixture of the powder of at least one aluminosilicate and of particles made of at least one metal or metalloid oxide.   
     
     
         40 . The method according to  claim 31 , further comprising:
 during step a), impregnating a fabric of fibers made of at least one metal or metalloid oxide with a slip or slurry of the powder of at least one aluminosilicate.   
     
     
         41 . The composite material according to  claim 28 ,
 wherein said particles are selected from particles of long fibers and short fibers or whiskers.   
     
     
         42 . The method according to  claim 38 ,
 wherein said particles are selected from particles of long fibers and short fibers or whiskers.